Effects of turbulators on flow development heat transfer in pipe flows

The aim of this study is to find the influence of helically coiled wires so called turbulators inserted in pipes on the flow field and heat transfer. An experimental set-up composed of pipe system and the blower unit providing controlled air flow for this purpose was designed and constructed. Helically coiled wires of different wire diameter, length, pitch, helix angle, number of coils were produced and tested. The tested turbulators covered a range of non-dimensional turbulator characteristics: D/d=13.33, 16, 20, 26.67: 50 < L/d < 300; 4.7 < n < 30; 5«; p/d < 21.3; 63.50 < a ^ 79° The influence of turbulators was investigated in a range of 30000^Re^ 90000 for which there existed a gap in the related literature.The experimental study was composed of two main parts. In the first part flow field measurements were conducted with turbulators inserted in the test pipe. The measurement of mean flow parameters were done by the pressure probes. In the second part temperature measurements were performed by means of copper-constantan thermocouples. The results of experimental investigation were given in comparison with the flow and heat transfer measurements made in the smooth empty test pipe. The hydrodynamic and thermal performance of turbulators were described by means of correlations between flow parameters and turbulator characteristic dimensions. Key Words: Turbulator, Smooth Pipe, Friction, Convective Heat Transfer Coefficient.